diff --git a/packages/ptc-runtime/ptc-runtime-node/tests/persistent-host.spec.ts b/packages/ptc-runtime/ptc-runtime-node/tests/persistent-host.spec.ts
new file mode 100644
index 0000000000..b585e1b6a6
--- /dev/null
+++ b/packages/ptc-runtime/ptc-runtime-node/tests/persistent-host.spec.ts
@@ -0,0 +1,215 @@
+import { Duplex, PassThrough } from 'node:stream'
+import { setImmediate } from 'node:timers/promises'
+import { Context } from '@deepseek-ai/cordis'
+import { describe, expect, it, onTestFinished, vi } from 'vitest'
+import FileSystem from '@deepseek-ai/dsh-fs-local'
+import Subprocess from '@deepseek-ai/dsh-subprocess-local'
+import type { PtcRunRequest } from '@deepseek-ai/dsh-ptc-runtime'
+import type { SubprocessHandle, SubprocessOutcome } from '@deepseek-ai/dsh-subprocess'
+import PersistentRuntime, { type Config } from '../src/persistent.ts'
+import { JsonChannel } from '../src/channel.ts'
+import { encodePtcJsonWire } from '../src/json-wire.ts'
+
+const request: PtcRunRequest = { program: '1', bindings: [], stateOwner: {} }
+const NO_INITIAL_FRAME = Symbol('no initial frame')
+async function setup(config: Config = {}) {
+  const ctx = new Context()
+  onTestFinished(async () => { await ctx.fiber.dispose() })
+  await ctx.plugin(FileSystem)
+  await ctx.plugin(Subprocess)
+  await ctx.plugin(PersistentRuntime, config)
+  const runtime = ctx.ptcRuntime
+  const control = new Duplex({
+    read() {},
+    write(chunk: Buffer, _encoding, callback) {
+      if (childControl.destroyed) { callback(new Error('peer closed')); return }
+      childControl.push(chunk)
+      callback()
+    },
+  })
+  const childControl = new Duplex({
+    read() {},
+    write(chunk: Buffer, _encoding, callback) {
+      if (control.destroyed) { callback(new Error('peer closed')); return }
+      control.push(chunk)
+      callback()
+    },
+  })
+  const stdout = new PassThrough()
+  const stderr = new PassThrough()
+  const direct = Promise.withResolvers<SubprocessOutcome>()
+  const messages: unknown[] = []
+  const terminate = vi.fn(() => {
+    stdout.end()
+    stderr.end()
+    direct.resolve({ exitCode: 0, signal: null })
+  })
+  const waitForExit = vi.fn(async () => true)
+  const handle: SubprocessHandle = {
+    stdin: undefined,
+    stdout,
+    stderr,
+    control,
+    collected: {},
+    done: direct.promise,
+    terminate,
+    waitForExit,
+  }
+  const writes = new Set<Promise<void>>()
+  let receive: (message: unknown) => void = () => {}
+  const peer = new JsonChannel(childControl, 1024 * 1024, (message) => {
+    messages.push(message)
+    receive(message)
+  }, () => {})
+  const emit = (message: unknown): void => {
+    const write = peer.send(message).catch(() => {}).finally(() => { writes.delete(write) })
+    writes.add(write)
+  }
+  const resolveExecutable = vi.spyOn(ctx.subprocess, 'resolveExecutable').mockResolvedValue(process.execPath)
+  const spawn = vi.spyOn(ctx.subprocess, 'spawn').mockReturnValue(handle)
+  onTestFinished(async () => {
+    peer.close()
+    control.destroy()
+    stdout.destroy()
+    stderr.destroy()
+    direct.resolve({ exitCode: 0, signal: null })
+    await Promise.all(writes)
+  })
+  const start = (input: PtcRunRequest = request, first: unknown = { type: 'ready' }) => {
+    const result = runtime.run(runtime.resolve(input))
+    if (first !== NO_INITIAL_FRAME) queueMicrotask(() => { emit(first) })
+    return result
+  }
+  const onBoot = (callback: () => void): void => {
+    receive = (message) => {
+      if (typeof message === 'object' && message !== null && 'type' in message && message.type === 'run') callback()
+    }
+  }
+  return {
+    ctx, runtime, handle, terminate, waitForExit, direct, stdout, stderr, control, peer, messages,
+    spawn, resolveExecutable, emit, start, onBoot,
+    receive: (callback: typeof receive) => { receive = callback },
+  }
+}
+
+function frame(payload: unknown, id = 1) { return { id, payload } }
+function call(id = 1, args: unknown = encodePtcJsonWire(null)) { return frame({ type: 'call', id, global: 'tools', name: 'test', args }) }
+const bound: PtcRunRequest = { ...request, bindings: [{ global: 'tools', functions: { test: async () => 42 } }] }
+
+describe('persistent PTC host protocol', () => {
+  it.each([
+    null,
+    { id: 99, payload: {} },
+    frame({ type: 'other' }),
+    frame({ type: 'log', text: 1 }),
+    frame({ type: 'done', error: { kind: 'other', message: '' } }),
+    frame({ type: 'done', error: { kind: 'exception', message: 1 } }),
+    call(2),
+    call(1, 'not a wire value'),
+  ])('rejects invalid process traffic %j', async (raw) => {
+    const h = await setup()
+    h.onBoot(() => { h.emit(raw) })
+    expect((await h.start(bound)).error?.kind).toBe('protocol')
+    expect(h.terminate).toHaveBeenCalledTimes(1)
+    expect(h.waitForExit).toHaveBeenCalledTimes(1)
+  })
+
+  it('requires the readiness handshake and all requested pipes', async () => {
+    const h = await setup()
+    expect((await h.start(request, { type: 'other' })).error?.kind).toBe('protocol')
+    const missing = await setup()
+    missing.spawn.mockReturnValue({ ...missing.handle, control: undefined })
+    expect((await missing.start(request, NO_INITIAL_FRAME)).error?.message).toContain('did not supply')
+  })
+
+  it.each(['exception', 'invalid-output', 'output-limit'])('accepts a terminal %s failure', async (kind) => {
+    const h = await setup()
+    h.onBoot(() => { h.emit(frame({ type: 'done', error: { kind, message: 'example' } })) })
+    expect((await h.start()).error?.kind).toBe(kind)
+  })
+
+  it('rejects lossy terminal values and bounds complete results', async () => {
+    const h = await setup()
+    h.onBoot(() => { h.emit(frame({ type: 'done', value: 'bad' })) })
+    expect((await h.start()).error?.kind).toBe('invalid-output')
+    const limited = await setup({ maxOutputBytes: 30 })
+    limited.onBoot(() => { limited.emit(frame({ type: 'log', text: 'x'.repeat(100) })) })
+    expect((await limited.start()).error?.kind).toBe('output-limit')
+  })
+
+  it('returns current binding successes, exceptions and unavailable bindings', async () => {
+    for (const functions of [{ test: async () => 42 }, { test: async () => { throw new Error('denied') } }, {}]) {
+      const h = await setup()
+      h.receive((raw) => {
+        const message = raw as Record<string, unknown>
+        if (message.type === 'run') h.emit(call())
+        else if (message.type === 'reply') h.emit(frame({ type: 'done', value: encodePtcJsonWire(message.ok === true) }))
+      })
+      const result = await h.start({ ...request, bindings: [{ global: 'tools', functions }] })
+      expect(result.error).toBeUndefined()
+      const reply = h.messages.find(raw => (raw as { type: string }).type === 'reply') as { ok: boolean; message?: string }
+      expect(result.value).toBe(reply.ok)
+      if (!reply.ok) expect(reply.message).toMatch(/denied|unavailable/)
+    }
+  })
+
+  it('bounds outstanding binding calls and drops replies after a run ends', async () => {
+    const h = await setup({ maxPendingCalls: 1 })
+    const pending = Promise.withResolvers<null>()
+    h.onBoot(() => { h.emit(call()); h.emit(call(2)) })
+    try {
+      expect((await h.start({ ...request, bindings: [{ global: 'tools', functions: { test: () => pending.promise } }] })).error?.kind).toBe('protocol')
+    } finally { pending.resolve(null) }
+    await setImmediate()
+    expect(h.messages.some(raw => (raw as { type: string }).type === 'reply')).toBe(false)
+  })
+
+  it('cleans up after launch failure and cancellation during executable resolution', async () => {
+    const h = await setup()
+    h.resolveExecutable.mockRejectedValue(new Error('missing executable'))
+    expect((await h.start(request, NO_INITIAL_FRAME)).error?.message).toContain('missing executable')
+    const waiting = await setup()
+    const ready = Promise.withResolvers<string>()
+    waiting.resolveExecutable.mockImplementation(() => ready.promise)
+    const controller = new AbortController()
+    const result = waiting.start({ ...request, signal: controller.signal }, NO_INITIAL_FRAME)
+    controller.abort()
+    ready.resolve(process.execPath)
+    expect((await result).error?.kind).toBe('abort')
+    expect(waiting.spawn).not.toHaveBeenCalled()
+  })
+
+  it('reports raw pipe output, stream errors and process failures without retaining state', async () => {
+    for (const action of ['raw', 'stream', 'exit', 'rejection'] as const) {
+      const h = await setup()
+      h.onBoot(() => {
+        if (action === 'raw') h.stdout.write('unattributed')
+        else if (action === 'stream') h.stderr.emit('error', new Error('pipe failed'))
+        else if (action === 'exit') h.direct.resolve({ exitCode: 7, signal: null })
+        else h.direct.reject(new Error('process failed'))
+      })
+      const result = await h.start()
+      expect(result.error?.kind).toBe(action === 'raw' ? 'protocol' : 'worker-exit')
+      expect(result.logs).toEqual([])
+    }
+  })
+
+  it('reports failed managed cleanup and waits for both exit and pipe drain', async () => {
+    const h = await setup()
+    h.waitForExit.mockRejectedValue(new Error('cleanup failed'))
+    h.onBoot(() => { h.emit(frame({ type: 'output-limit' })) })
+    expect((await h.start()).error?.message).toContain('cleanup failed')
+  })
+
+  it('rejects invalid resolved inputs and deployment bounds', async () => {
+    const h = await setup()
+    await expect(h.runtime.run({ ...request, cwd: '.', timeoutMs: null })).rejects.toThrow('resolved inputs')
+    await expect(h.runtime.run({ ...request, cwd: process.cwd(), timeoutMs: Infinity })).rejects.toThrow('resolved inputs')
+    for (const config of [
+      { timeoutMs: 0 }, { maxMessageBytes: 0x1_0000_0000 }, { maxOutputBytes: 3 }, { graceMs: 2_147_483_648 },
+      { nodeExecutable: '' }, { bootstrapPath: 'relative' },
+    ]) {
+      await expect(setup(config)).rejects.toThrow('persistent PTC')
+    }
+  })
+})
diff --git a/packages/ptc-runtime/ptc-runtime-node/tests/persistent-process.spec.ts b/packages/ptc-runtime/ptc-runtime-node/tests/persistent-process.spec.ts
index a6a2cfb147..208e2254a6 100644
--- a/packages/ptc-runtime/ptc-runtime-node/tests/persistent-process.spec.ts
+++ b/packages/ptc-runtime/ptc-runtime-node/tests/persistent-process.spec.ts
@@ -57,7 +57,11 @@ it('keeps an environment while capturing each evaluation and binding replies sep
 })
 
 it('contains directory failures and output overflow in the active evaluation', async () => {
-  const badDirectory = await setup(4096, () => { throw new Error('directory missing') })
+  const badDirectory = await setup(4096, () => {
+    const error = new Error('directory missing')
+    error.stack = 'Error: directory missing'
+    throw error
+  })
   expect(await badDirectory.run('1')).toMatchObject({ error: { kind: 'exception', message: expect.stringContaining('directory missing') } })
   const h = await setup()
   await h.run('console.log("x".repeat(100))', [], 20)